Everytime I read the Harry Potter books, I am amazed by the perception which lead J K Rowling to label dementors as the most loathsome creatures in Potterland. I mean, creatures that come by sucking all the positive energy you have and recalling the worst times of your life. Being around dementors saddens you, depresses you and finally drives you crazy.
Dementors are not merely creatures of Rowling's imagination. Muggle versions inhabit our world too. You may be celebrating your new promotion and there will be this one person who comes by and says, “I’m so happy you got a promotion. At least it will keep your mind off the fact that you are not yet married.” And that is enough to suck the atmosphere of all the festive cheer.